From 5030242cb2f61656a13b01d18cab8f69b0602efe Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 14 Mar 2019 23:46:05 -0400 Subject: [PATCH] ext4: avoid panic during forced reboot BugLink: https://bugs.launchpad.net/bugs/1830906 [ Upstream commit 1dc1097ff60e4105216da7cd0aa99032b039a994 ] When admin calls "reboot -f" - i.e., does a hard system reboot by directly calling reboot(2) - ext4 filesystem mounted with errors=panic can panic the system. This happens because the underlying device gets disabled without unmounting the filesystem and thus some syscall running in parallel to reboot(2) can result in the filesystem getting IO errors. This is somewhat surprising to the users so try improve the behavior by switching to errors=remount-ro behavior when the system is running reboot(2). Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin Signed-off-by: Stefan Bader Signed-off-by: Kleber Sacilotto de Souza --- fs/ext4/super.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 21a7d00878d1..adcc3d590ed1 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -435,6 +435,12 @@ static void ext4_journal_commit_callback(journal_t *journal, transaction_t *txn) spin_unlock(&sbi->s_md_lock); } +static bool system_going_down(void) +{ + return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF + || system_state == SYSTEM_RESTART; +} + /* Deal with the reporting of failure conditions on a filesystem such as * inconsistencies detected or read IO failures. * @@ -465,7 +471,12 @@ static void ext4_handle_error(struct super_block *sb) if (journal) jbd2_journal_abort(journal, -EIO); } - if (test_opt(sb, ERRORS_RO)) { + /* + * We force ERRORS_RO behavior when system is rebooting. Otherwise we + * could panic during 'reboot -f' as the underlying device got already + * disabled. + */ + if (test_opt(sb, ERRORS_RO) || system_going_down()) { ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only"); /* * Make sure updated value of ->s_mount_flags will be visible @@ -473,8 +484,7 @@ static void ext4_handle_error(struct super_block *sb) */ smp_wmb(); sb->s_flags |= SB_RDONLY; - } - if (test_opt(sb, ERRORS_PANIC)) { + } else if (test_opt(sb, ERRORS_PANIC)) { if (EXT4_SB(sb)->s_journal && !(EXT4_SB(sb)->s_journal->j_flags & JBD2_REC_ERR)) return; -- 2.39.5